AutoX Tire Wear

AyJay87 · 10-07-2015, 12:43 AM

Recently went autocrossing and I noticed a darker, 1" wide band/region towards the outside shoulder of the tires. What does your intuition say this is? And the cause?

My best guess is not enough negative camber or just build up of rubber from the course. Here's some data:

225 MPSS front
245 MPSS rear
28mm front sway bar
15 mm rear sway bar
-2.1 deg front camber
-1.7 deg rear camber
pavement temp about 125 deg F
95 deg F ambient

alpho · 10-07-2015, 08:27 AM

Is it on both front and rear? or only front? what tire pressure's were you running?

Kgolf31 · 10-07-2015, 09:02 AM

Most likely a compound change at the edge of the shoulder.

And yes, no where near enough camber.

Pictures would be helpful

AyJay87 · 10-07-2015, 09:44 AM

Quote:

Originally Posted by alpho

Is it on both front and rear? or only front? what tire pressure's were you running?

It is more on the fronts than the rears. Cold tire pressures: 36 psi front, 39 psi rear.

AyJay87 · 10-07-2015, 09:45 AM

Quote:

Originally Posted by Kgolf31

Most likely a compound change at the edge of the shoulder.

And yes, no where near enough camber.

Pictures would be helpful

That right, there is a different compound on the outside edge. What camber would you recommend? I'll see if I can get a good picture later.

dtla1 · 10-09-2015, 10:45 AM

The experts might chime in here, but I think that cold tire pressure is a little too high. Also, more camber. And MPSS shoulders are very soft, easy for you to roll the tire over.

AyJay87 · 10-10-2015, 03:22 PM

Quote:

Originally Posted by dtla1

The experts might chime in here, but I think that cold tire pressure is a little too high. Also, more camber. And MPSS shoulders are very soft, easy for you to roll the tire over.

What pressure should I run cold?

AyJay87 · 10-10-2015, 03:25 PM

Quote:

Originally Posted by Kgolf31

Most likely a compound change at the edge of the shoulder.

And yes, no where near enough camber.

Pictures would be helpful

Finally got a picture, though its not great. Its dusty/dirty. You can kind of see it. The flash kind of hides it towards the middle-top of the pic.

Kgolf31 · 10-10-2015, 11:02 PM

Quote:

Originally Posted by AyJay87

Quote:

Originally Posted by Kgolf31

Most likely a compound change at the edge of the shoulder.

And yes, no where near enough camber.

Pictures would be helpful

Finally got a picture, though its not great. Its dusty/dirty. You can kind of see it. The flash kind of hides it towards the middle-top of the pic.

It's extra heat generated on the outside shoulder. I've had tires in that spot turn to purple

lowside67 · 10-11-2015, 02:32 PM

That looks to me to easily be attributed to camber, not pressure. You are going to need in excess of 3 degrees to properly evenly wear your front tires.

Mark

10-07-2015, 12:43 AM	#1
AyJay87 Private First Class 8 Rep 122 Posts Drives: 2012 135i DCT Le Mans Blue Join Date: Jul 2014 Location: SoCal iTrader: (0)	AutoX Tire Wear Recently went autocrossing and I noticed a darker, 1" wide band/region towards the outside shoulder of the tires. What does your intuition say this is? And the cause? My best guess is not enough negative camber or just build up of rubber from the course. Here's some data: 225 MPSS front 245 MPSS rear 28mm front sway bar 15 mm rear sway bar -2.1 deg front camber -1.7 deg rear camber pavement temp about 125 deg F 95 deg F ambient __________________ https://www.instagram.com/the_driving_gallery/ '12 135i DCT Le Mans Blue * M Sport Package * BMW Performance Exhaust * PPK 1 * ST Coilovers * Cobb Sway Bars * Dinan Camber Plates * VMR V705 Wheels * Michelin PSS
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10-07-2015, 08:27 AM	#2
alpho New Member 8 Rep 28 Posts Drives: AW 135i Join Date: Mar 2015 Location: Illinois iTrader: (0)	Is it on both front and rear? or only front? what tire pressure's were you running?
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10-07-2015, 09:02 AM	#3
Kgolf31 Brigadier General 460 Rep 4,531 Posts Drives: 2007 Z4MC, 2012 128i Join Date: Sep 2008 Location: Ohio iTrader: (4)	Most likely a compound change at the edge of the shoulder. And yes, no where near enough camber. Pictures would be helpful
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10-09-2015, 10:45 AM	#6
dtla1 Colonel 828 Rep 2,232 Posts Drives: 2011 135i, Space Grey Join Date: Apr 2014 Location: Silicon Valley iTrader: (2)	The experts might chime in here, but I think that cold tire pressure is a little too high. Also, more camber. And MPSS shoulders are very soft, easy for you to roll the tire over.
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10-11-2015, 02:32 PM	#10
lowside67 First Lieutenant 219 Rep 361 Posts Drives: 2011 BMW 128i Join Date: Apr 2015 Location: Vancouver, Canada iTrader: (0)	That looks to me to easily be attributed to camber, not pressure. You are going to need in excess of 3 degrees to properly evenly wear your front tires. Mark __________________ 2011 BMW 128i - Check out my STX build thread!
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